The present invention relates to an improved single crystal nickel base superalloy having a pore-free, eutectic γ–γ′ free microstructure with a modified gamma-prime morphology and to a process for making the improved nickel base superalloy.
Mechanical property tests of cast nickel-base superalloys have shown substantial deleterious effects when conducted in high pressure gaseous hydrogen environments. These effects include reductions in tensile ductility and strength, fatigue and accelerated crack growth rates. Thus, there is a need to develop a nickel base superalloy which avoids these deleterious effects.